How to effectively fight corruption

The revelations in recent days of one of the world's largest financial institutions HSBC advising wealthy clients on how best to avoid paying a fair share in tax has come to light. This is nothing new as since the global financial crisis of Protected content banks have come under the spotlight for there lending practices (subprime loans market), fixing interest rates (LIBOR), or money laundering activities (HSBC). There is alot and many different facets to the general discussion of corporate and financial corruption and it's effects of the global financial system and how it undermines integrity and the trust we have with the banking system. I just wanted to open up a discussion on possible solutions that can be proposed to stop this kind of activity from constantly recurring and the potential for it to bring down the entire financial system in which we all operate. Should there be more government regulation. Should financial institutions be nationalised or is it simply a case of a few criminal individuals in high position. It would be good to hear everyone's view on this.